The primary role of the cardiovascular system is to facilitate adequate circulating blood volume to provide sufficient oxygen delivery, thereby meeting the metabolic demands of the tissues and cells. The adequacy of circulating blood volume may be affected by the functional effectiveness of the cardiovascular system. A healthy cardiovascular system may be characterized, in part, by its ability to maintain adequate oxygenated blood flow and pressure in response to changes in the demand for oxygenated blood. Such changes may result from traumatic stresses or changes in the metabolic health of tissues or organs reflected in their ability to extract or use oxygenated blood. An impaired cardiovascular system may not be able to supply sufficient oxygen to tissues or adapt to circulatory stress. If oxygen delivery to tissue has been compromised, tissue hypoxia may occur. If tissue hypoxia is prolonged, acute cellular or organ damage may occur resulting in long term patient morbidity or mortality.
Cardiovascular impairment can occur due to sudden pathology or trauma, resulting in shock. Alternatively, such impairment may occur in resting patients due to underlying chronic pathologies, such as heart failure. Additionally, external volemic stressors, including some medical procedures, may cause fluid to transfer into or out of the arterial tree. As one example, ultrafiltration used for kidney replacement therapy may result in an induced hypovolemic condition due to a mismatch between the rate of volume removal from the vasculature and the rate of refill of fluid volume from outside of the vasculature. In another example, poor management of aquapheresis therapy for heart failure patients having cardiac pulmonary edema may also result in a significant change in patient fluid volume. Thus, a hypovolemic condition may be induced if too much fluid is removed, or residual edema may result if too little is removed. For patients undergoing surgery, the vasodilation effects of analgesics and paralytics may result in too little effective or maintained fluid volume. Alternatively, surgical patients may receive excess fluid volume from intravascular administration of normal saline solution.
While hemodynamic dysfunction conditions may be present in an acute care setting, the initial onset of such conditions may begin in other venues with or without the patient presenting any related symptoms. Some non-limiting examples of such non-acute care settings may include clinics, physician offices, nursing homes, pre-hospital emergent care transport facilities, transitional care facilities, and the home. It may be understood that accurate detection of pre-symptomatic or early symptomatic hemodynamic dysfunction by caregivers in these non-acute settings may permit the caregivers to intervene proactively, thereby avoiding a possible acute event or a least minimizing the adverse effects on the patient. Typically, only non-invasive medical device technologies are tolerated in such non-acute care settings. Additionally, caregivers at these facilities may not have sufficient or detailed medical training to recognize when a patient has a hemodynamically unstable condition, or to accurately diagnose the type of dysfunction and provide the necessary care.